const weight = { weight: '50kg' }
const age = { age: 18 }

const Bob = Object.assign(weight, age)

console.log(weight) // 缺陷1: 目标对象 weight 也会受到影响
console.log(Bob) //=> 都是 { weight: '50kg', gender: 'male' }

console.log('=== 为了避免修改原始对象，我们通常会这样做：===')

const Alice = Object.assign({}, weight, age)
console.log(Alice) //=> { weight: '50kg', age: 18 }
